Wafer holder and wafer conveyor system equipped with the same

ABSTRACT

The present invention is directed to a wafer holder and a related wafer conveyor system. The wafer holder holds a wafer and moves horizontally within a chamber. A contact area between the wafer and the wafer holder is reduced, and potential contaminants generated by ear between components of the wafer holder are trapped by an airtight cover. Since the wafer holder moves horizontally while being fixed to a guide rail, the wafer conveyor system reduces friction between the guide rail and the wafer holder.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an apparatus for use in asemiconductor fabricating process. More specifically, the presentinvention relates to a wafer holder and a wafer conveyor system equippedwith the wafer holder.

A claim of priority is made to Korean Patent Application No. 2003-95618filed on Dec. 23, 2003, the disclosure of which is incorporated hereinby reference in its entirety.

2. Description of Related Art

In a conventional semiconductor fabricating process, an integratedcircuit device is fabricated by forming a pattern on a semiconductorwafer, and monitoring the pattern-formed wafer. From a preparation area,a wafer is transferred to an operating area for fabrication and testing.The wafer is placed on an apparatus with its pattern-formed front sideor back side facing up depending on the configuration of the fabricatingapparatus or the test apparatus. When the wafer's front side is facingdown, edges of the wafer is supported by a wafer holder.

As shown in FIG. 1 and FIG. 2, a wafer 18 disposed on a wafer holder(not shown) and in a preparation area of a chamber 10 is safelytransferred to an operation area 18′. A wafer-input opening 14 adaptedto load wafer 18 into chamber 10 is formed over the preparation area; atest apparatus 12 adapted to monitor the surface of wafer 18 isinstalled under the operation area.

FIG. 2 shows a conventional wafer conveyor system having a pair ofparallel guide rails 20 adapted to linearly move a wafer holder. Athread 20 a is formed on a surface of the respective guide rails 20. Awafer holder 25 is disposed between guide rails 20. A base plate 24 ofwafer holder 25 has sawtooth-shaped protrusions 24 a located where baseplate 24 and guide rail 20 come in contact. As guide rails 20 rotate,the sawtooth-shaped protrusions 24 a move in conjunction with thread 20a. Thus, wafer holder 25 transfers back and forth between thepreparation area and the operation area.

Disposed about its center, base plate 24 has a hollow section 40. Arotatable supporter ring 26 is provided in hollow section 40. In theconventional art, a cylindrical roller 30 and a shaft 22 function as arotating means. Cylindrical roller 30 is horizontally disposed on baseplate 24 along the outer perimeter of supporter ring 26. Shaft 22 isconnected along a pivot to rotate roller 30. Roller 30 is also threaded.

FIG. 3 illustrates in some additional detail the conventional waferholder 25. Wafer holder 25 includes supporter ring 26 and a wafer guidering 28. Supporter ring 26 is disposed in hollow section 40, and waferguide ring 28 is disposed inside supporter ring 26. A portion ofsupporter ring 26 is buried in base plate 24, but sawtooth-shapedprotrusions 26 a protrude from base plate 24. Sawtooth-shapedprotrusions 26 a engage the thread of roller 30. When roller 30 rotatesby the driving action of shaft 22, the thread of roller 30 engages thesawtooth-shaped protrusions 26 a to rotate supporter ring 26. A liner 34is formed along the inner wall of wafer guide ring 28. The outer edge ofwafer 18 is supported by liner 34. The pattern-formed side of wafer 18faces down on liner 34.

In the conventional wafer conveyor system, when guide rail 20 rotates,sawtooth-shaped protrusions 24 a move along thread 20 a. Since themovement of wafer holder 25 is perpendicular to the rotational directionof guide rail 20, friction between the sawtooth-shaped protrusions 24 aand thread 20 a causes the respective parts to wear out. If a part isworn out, time is lost in production when the worn out part ismaintained or replaced. Furthermore, frictional wear in a systemoperating within a clean room environment may further cause particlecontamination. If metallic particles become attached to a wafer surface,an integrated circuit device formed on the wafer may become defective,or the entire fabrication process may become contaminated.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a wafer holder to safelysupport a wafer while reducing the contact area with the wafer.

In another aspect, the preset invention provides a wafer holder whichreduces potential contamination of the wafer.

In still another aspect, the present invention provides a wafer conveyorsystem capable of reducing potential contamination of the wafer.

In order to achieve these aspects, the present invention provides awafer holder reducing an area of contact between the wafer holder andthe wafer. The wafer holder comprises a base plate, a rotatablecylindrical roller, a supporter ring, and a wafer guide ring. The baseplate has a circular hollow part and ring-shaped grooves formed alongedges of a circular hollow part. The cylindrical roller is adjacent toan outer side of the guide groove to be horizontally installed at thebase plate. A thread is formed at a circumferential surface of thecylindrical roller, and a shaft hole is formed at a shaft of thecylindrical hole. The supporter ring is inserted into the guide grooveto expose a circumferential surface of the supporter ring to an upperportion of the base plate. Sawtooth-shaped protrusions are formed alongthe exposed circumferential surface of the supporter ring to gear withthe thread of the cylindrical roller. The wafer guide ring isattachably/removably mounted on the supporter ring. A plurality of padsare formed at an inner circumferential surface of the wafer guide ringto support the wafer's edge.

The wafer holder may further comprise a cover to prevent particlesgenerated by abrasion of components (or parts) from being scattered. Thecover is combined with the base plate to seal the sawtooth-shapedprotrusions and cylindrical roller combination from the outside. A holecorresponding to the shaft hole is formed at the cover, so that thecylindrical roller is driven using the shaft. The shaft is connected tothe cylindrical roller through the hole of the cover.

According to another aspect of the present invention, the presentinvention provides a wafer conveyor system for conveying a wafer in achamber. The wafer conveyor system comprises driving rollers and passiveroller oppositely disposed at both sides of the chamber with a regularspace and first and second rails whose inner surface are in contact withthe respective driving rollers and passive roller. The first and secondrails are oppositely disposed and drive in the same direction. A waferholder disposed between the first and second guide rails. The first andsecond guide rails are connected to both sides of the wafer holder toallow the wafer holder to move in parallel with the driving direction ofthe first and second rails.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional fabrication process system having a waferconveyor system.

FIG. 2 shows a conventional wafer conveyor system.

FIG. 3 is a detail perspective view of a conventional wafer holder.

FIG. 4 shows a wafer conveyor system according to a preferred embodimentof the present invention.

FIG. 5 is a top plan view of a wafer conveyor system according to anembodiment of the present invention.

FIG. 6 is a detail perspective view of the wafer holder according to anembodiment of the present invention.

FIG. 7 is an exploded view of the wafer holder according to anembodiment of the present invention.

FIG. 8 is an exploded view of a wafer holder according to anotherembodiment of the present invention.

FIG. 9 is a detail perspective view of the wafer holder of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

A wafer conveyor system 100 according to the present invention isillustrated in FIG. 4. Referring to FIG. 4, wafer conveyor system 100comprises guide rails 152, further comprises a first guide rail 152 aand a second guide 152 b. A set of driving rollers 150 a and a set ofpassive rollers 150 b are spaced apart from each other, with each sethaving one roller disposed in relation to the first guide rail 152 a andsecond guide rail 152 b, respectively. The inner portion of guide rails152 a, 152 b contacts and wraps around driving roller 150 a and passiveroller 150 b.

A wafer holder 110 is disposed between first and second guide rails 152a, 152 b, and horizontally moves within a chamber in response to themovement of guide rails 152 a, 152 b. Namely, wafer holder 110 istransferred between a preparation area and an operation area on conveyorsystem 100.

Wafer conveyor system 100 optionally comprises a plurality ofsub-rollers 154 installed between respective combinations of drivingroller 150 a and passive roller 150 b. Sub-rollers 154 help preventguide rails 152 a, 152 b from sagging, thus assisting in the safemovement of wafer holder 110. Although not illustrated, guide rails 152a, 152 b are preferably flexible, except at those areas where the waferholder 110 is fixed thereto.

Wafer holder 110 according to the present invention is fixed to guiderails 152 a, 152 b. Therefore, contamination generated by wear of guiderails 152 a, 152 b and wafer holder 110 is minimized.

Referring to FIG. 5, FIG. 6, and FIG. 7, wafer holder 110 includes abase plate 112, a supporter ring 116, and a guide ring 118 mounted on aninner portion of the supporter ring 116. Base plate 112 is mounted onguide rails 152 a, 152 b. About its center, base plate 112 has a hollowsection 140. A ring-shaped guide groove 134 is formed in base plate 112.Supporter ring 116 is inserted into guide groove 134. Sawtooth-shapedprotrusions 124 protrude from supporter ring 116 over base plate 112.Supporter ring 116 rotates along guide groove 134.

A cylindrical roller 120 is combined with base plate 112. A thread 128is formed on a circumferential surface of cylindrical roller 120.Cylindrical roller 120 rotates on a shaft 122, which is horizontallycombined with base plate 112. Rotation of cylindrical roller 120 enablesthread 128 to engage sawtooth-shaped protrusions 124, thus rotatingsupporter ring 116. A rotation angle of supporter ring 116 is regulatedaccording to the number of rotations for roller 120.

A removable wafer guide ring 118 is engaged with supporter ring 116. Aplurality of pads 130, which support edges of a wafer, are arrangedalong an inner circumferential surface of guide ring 118. Pads 130further comprise a supporter 130 a to support the wafer's edge, and aslide 130 b to safely guide the wafer onto supporter 130 a. Guide ring118 is in contact with the wafer's edge via pads 130; therefore, pads130 prevent materials on edges of a wafer from falling out, because thewafer is not in direct contact with guide ring 116. In the presentinvention, supporter ring 116 and cylindrical roller 120 are capsulatedby a cover 114. Cover 114 also prevents contaminants from scatteringwhen sawtooth-shaped protrusions 124 and thread 128 mechanically wear.Cover 114 preferably has a ring-shaped section 114 c, which coverssupporter ring 116, and a housing section 114 h, which extends fromring-shaped section 114 c to cover cylindrical roller 120. (See FIG. 7).A cover groove 132 is formed on base plate 112 to secure cover 114. Aninsertion hole 126, wherein shaft 122 of roller 120 is inserted, isformed in housing section 114 h. Roller 120 slides along shaft 122.

FIG. 8 is an exploded view of a wafer holder 210 according to a secondembodiment of the present invention. FIG. 9 is a perspective view ofwafer holder 210 according to the second embodiment of the presentinvention.

Referring to FIG. 8 and FIG. 9, wafer holder 210 according to the secondembodiment of the invention includes a supporter ring 216, and a cover214. Cover 214 preferably comprises a ring-shaped section 214 a to coversupporter ring 216, and a housing section 214 c, which extends fromring-shaped section 214 a. A cap 214 b is inserted between a base plate212 and supporter ring 216. Housing section 214 c covers supporter ring216, and extends over and covers sawtooth-shaped protrusions 224. Cover214 and a supporter ring 218 are inserted into a guide grove 234, whichis formed in base plate 212. Cover 214 is fixed to guide groove 234.Supporter ring 216 rotates in conjunction with the rotation of acylindrical roller 220. Base plate 212 has a cover groove 232 wherehousing section 214 c is inserted therein. Cover groove 232 extends fromguide groove 234 to surround a portion containing cylindrical roller220. Thus when roller 220 is combined with base plate 212, housingsection 214 c is combined with groove 232 to cover roller 220. A thread228 of roller 220 engages sawtooth-shaped protrusions 224 of supporterring 216.

A removable wafer guide ring 218 engages with supporter ring 216. Aplurality of pads 230 for supporting a wafer's edge are installed on aninner circumferential surface of guide ring 218. Pads 230 furthercomprise a supporter 230 a to support the wafer's edge, and a slide 230b to safely guide the wafer onto supporter 230 a.

A wafer is supported by pads 230 of guide ring 218. Thus, the contactarea between the wafer and wafer holder 210 is reduced, thus preventingmaterials on the wafer from falling down. Slide 230 b correctsmisaligned wafers by guiding the wafers into the correct position alongslide 230 b onto supporter 230 b. Wafer holder 210 rotates a wafer inconjunction with cylindrical roller 220 and supporter ring 216.Supporter ring 216 and cylindrical roller 220 are sealed from theoutside by cover 214. Cover 214 prevents contaminants from scatteringfrom supporter ring 216 and cylindrical roller 220.

While the present invention has been described in detail with referenceto the presently preferred embodiments, those skilled in the art willappreciate that various modifications may be made without departing fromthe scope of the invention. Accordingly, the invention is defined by thefollowing claims.

1. A wafer holder comprising: a base plate having a guide groove formedaround a centrally located hollow section; a threaded cylindrical rollerinstalled on the base plate adjacent to the guide groove; a supporterring having sawtooth-shaped protrusions provided in the guide groove,wherein the sawtooth-shaped protrusions engage the threaded cylindricalroller; a wafer guide ring mounted in the supporter ring; and a coverintegrally installed on the base plate to cover the sawtooth-shapedprotrusions of the supporter ring and the threaded cylindrical roller.2. The wafer holder of claim 1, further comprising a plurality of padsformed on an inner surface of the wafer guide ring and adapted toreceive and support a wafer.
 3. The wafer holder of claim 2, wherein theplurality of pads further comprises: a supporter adapted to support anedge of the received wafer; and a slide to guide the wafer into positionon the supporter.
 4. The wafer holder of claim 1, wherein the base platefurther comprises a cover groove formed around the hollow section andadapted to receive a edge of the installed cover.
 5. The wafer holder ofclaim 1, wherein the cover completely covers the operative combinationof the supporter ring and the threaded cylindrical roller.
 6. The waferholder of claim 5, further comprising a cap inserted between the covergroove and the supporter ring.
 7. The wafer holder of claim 1, whereinthe wafer guide ring is removable from the supporter ring.
 8. The waferholder of claim 1, wherein the base plate is adapted for mounting ontoat least one guide rail.
 9. A wafer holder comprising: a base platehaving a hollow section therein and a guide groove formed along an edgeof the hollow section; a cylindrical roller installed on the base plateadjacent to the guide groove, wherein the cylindrical roller isthreaded; a supporter ring having sawtooth-shaped protrusions providedin the guide groove, wherein the sawtooth-shaped protrusions engage thethread of the cylindrical roller; a wafer guide ring mounted in thesupporter ring; a plurality of pads formed along an inner surface of thewafer guide ring, pad comprising a supporter having a horizontal uppersurface adapted to support an edge of a wafer and a slide having asloped upper surface extending to the horizontal upper surface of thesupporter adapted to guide the wafer into a position on the supporter.10. The wafer holder of claim 9, further comprising a cover to protectthe sawtooth-shaped protrusions and the cylindrical roller.
 11. Thewafer holder of claim 10, further comprising a cover to protect thesupporter ring and the cylindrical roller.
 12. The wafer holder of claim10, wherein the base plate further comprises a cover groove formed at anupper portion of the base plate and surrounding the circular hollowsection, wherein the cover is inserted into the ring-shaped covergroove.
 13. The wafer holder of claim 11, wherein a cap is insertedbetween the cover groove and the supporter ring.